Growing environmental concerns about pollution and air quality have increased the emphasis on the amount of pollutants in motor vehicle emissions.
For example, most vehicles now include a monitoring system called an on-board diagnostic system. The on-board diagnostic system monitors the performance of some of a motor vehicle's major components, including those responsible for controlling emissions. The Environmental Protection Agency (EPA) requires all cars to be manufactured with an on-board diagnostic system. One of the purposes of the on-board diagnostic system is to alert the operator when an engine condition exists that requires immediate attention. For example, if the on-board diagnostic system detects that the exhaust from the motor vehicle is exceeding emission standards, it will initiate an alarm by lighting up a malfunction indicator light. The operator can then take the motor vehicle to a service station in order to determine the cause of the problem.
The use of alternative fuels is also being explored to improve the environmental air quality. For example, ethanol fuel (E85) has a higher octane rating than conventional methanol gasoline, which means that ethanol fuel burns more efficiently and more cleanly. However, it is difficult to start engines using ethanol fuel at cold temperatures. This problem can be overcome by injecting extra ethanol fuel into the engine during startup. However, this extra fuel will carry over into the engine's exhaust and may cause the engine's on-board detection system to light up the malfunction indicator light on the dashboard.
It is impractical for the on-board diagnostic system to indicate a malfunction each time the motor vehicle starts in cold temperatures.